Pacific Underwater Calendar: Spring is in the air — and the water

Spring is on the way, and with it, marine mammals such as grey whales, northern fur seals and sea otters travel thousands of kilometres to feed and give birth in more hospitable Pacific coastal waters.

After spending the winter in waters off the Baja peninsula, thousands of Pacific grey whales travel north in March. While most finish their migration in the Bering Sea, some choose B.C.'s coast as their final destination.

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Although they're the only bottom-feeding whale, they display stereotypical whale characteristics: barnacle-covered, huge (at 15 metres long) and lacking dorsal fins. Every day, each whale swallows more than 1,000 kilograms of shrimp, worms and fish from the sea floor, filtering the food through baleen plates.

Northern fur seals can also be seen travelling along the North Pacific this time of year, with sightings common in the Hecate Strait near Haida Gwaii. Home turf ranges from Japan to southern California and up to the Bering Sea. B.C.'s coastal waters are important foraging areas, especially for pregnant females, which will then return to popular Alaskan rookeries.

They have characteristic external ears (pinnae), long muscular foreflippers and thick fur coats. Males are up to 40 per cent longer and more than four times heavier than females. They have a varied and broad taste palette, feeding on fish (pollock, herring, salmon, mackerel and anchovies), squid and occasionally birds. They are preyed on by sharks and orcas.

Fur seals spend more than half the year in the open ocean and sleep on their backs, their fins sticking out of the water like jug handles. Pups can remain at sea for up to 22 months.

Sea otters off the North Pacific coast give birth in spring. They mate, sleep, hunt and give birth off the west coast of Vancouver Island and in central coastal waters. Newborn pups float like corks, aided by lanugo coats that take at least two months to shed before the pups can start diving. Mothers float on their backs and care for their babies on their stomachs.

These charismatic creatures can be found swimming and resting in kelp forests, bays, reefs and fjords, floating on their backs and feasting on local delicacies such as clams, mussels, chitons, prawns, abalone and sea urchins. Because sea otters' feeding habits can affect the entire ecosystems in which they live, they have an important influence on habitat and marine life in kelp forests. They rely on touch, using their agile front paws and whiskers to find food. These voracious eaters swallow up to 30 per cent of their body weight each day and are one of the few mammals that use tools, such as rocks, to pry and split shellfish. They store food in loose skin pockets under their forearms. Orcas, sharks and bald eagles often eat sea otters.

Dwindling numbers

Grey whales
Although hunting bans have helped grey whale populations rebound to about 18,000 in B.C. they remain a "species of concern" under federal law.
They face threats from orcas, industrial pollution, fishing gear, noise and propeller cuts from marine vessels and warming and acidifying oceans related to climate change. With the possibility of increased tanker shipping, these whales still aren't in safe waters.

Threats include availability of prey, changes in ocean conditions, marine debris, environmental pollutants and interactions with vessels and humans.

Sea otters
By the 1800s, sea otters had been hunted to extinction along B.C.'s coast. The good news is they've now recovered to 5,000 and have been down-listed from "threatened" to "special concern". B.C.'s otters are the descendants of 89 relocated Alaskan sea otters.
Threats include availability of prey, oil spills and environmental contamination and conflicts with commercial fisheries.

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